Hydraulic grabs for use in ground levelling operations



March 8, 1966 GUINQT 3,239,083

HYDRAULIC GRABS FOR USE IN GROUND LEVELLING OPERATIONS Filed June 23, 1964 2 Sheets-Sheet 1 March 8, 1966 sumo-r 3,239,083

HYDRAULIC GRABS FOR USE IN GROUND LEVELLING OPERATIONS Filed June 23, 1964 2 Sheets-Sheet 2 Fig. 2

United States Patent 3,239,083 HYDRAULIC GRABS FOR USE IN GROUND LEVELLING OPERATIONS Gabriel Guinot, Le Plessis-Belleville, France, assignor to Societe Anonyme Poclain, Le Plessis-Belleville (Oise), France, a French society Filed June 23, 1964, Ser. No. 377,349 Claims priority, application France, July 12, 1963,

941,217 Claims. (Cl. 214-138) The present invention relates to improvements in hydraulic grabs and in particular to hydraulic grabs for use in ground levelling operations.

There are already numerous known types of hydraulic grabs comprising a chassis (or turret pivoting about a vertical axis) carrying a jib which is articulated about a horizontal axis and the inclination of which is controlled by a hydraulic jack. The jib supports a beam which oscillates about a generally horizontal axis, and which itself supports a tool, for example a levelling bucket likewise capable of pivoting about a horizontal axis at the lower end of the beam.

For levelling work, the bucket must remain in a substantially constant position with respect to the ground while the beam is oscillating on the jib. For this purpose, some arrangments have already been proposed wherein the beam is made up of two parallel links of equal length articulated to the jib, the bucket being itself articulated to the lower end of the said links. Finally, there is usually provided an hydraulic jack articulated to one of the links of the beam, and either directly to the jib or to the chassis or turret. This latter jack enables the oscillatory movement of the beam to be controlled in order to carry out levelling work, the jib-orientating jack then being entirely free to extend or retract the beam.

In another known leveller device a beam is articulated to the end of a jib capable of oscillating on its carrier chassis, the said beam pivotally supporting a tool, for example a bucket, the angular position of which relative to the ground is controlled, while the beam is oscillating on the jib, by means of a unit comprising a first rocking lever articulated to the beam and a second rocking lever articulated to the jib, and three links, one of the latter being attached to the tool and to the first rocking lever, while another is attached to both rocking levers.

However, these known hydraulic grabs do not normally satisfy the requirements for unloading, for example on to a vehicle, materials loaded into the bucket. In cases when these known grabs enable unloading to be carried out, they necessarily comprise relatively complicated means in order to enable the bucket to oscillate to a sufiicient degree on the beam.

An object of the present invention is to provide an improved hydraulic grab, in particular for ground levelling purposes, which overcomes the above described disadvantages common to the known constructions of grabs.

According to the invention, the hydraulic grab comprises a beam articulated to the end of an oscillatable jib and pivotally supporting a tool, for example a bucket, the angular position of which relative to the ground is controlled, while the beam is oscillating on the jib, by means comprising a first rocking lever articulated to the beam and a second rocking lever articulated to the jib, and three links, one of which is pivoted to the tool and to the first rocking lever, while another is pivoted to both rocking levers, characterised in that the third link is pivoted to the second rocking lever and to the beam, the axis of articulation of the first rocking lever being disposed in the vicinity of the point where the tool is articulated to the beam, While the axis of articulation of the second rocking lever is disposed in the vicinity of the point at which the beam is articulated to the jib.

In order that the invention may be more clearly understood various embodirnents thereof will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a side elevation of a grab according to the invention in its ground levelling position (full lines) and in the unloading position (dotted lines),

FIGURE 2 is a similar view of a modified embodiment of the grab illustrated in FIGURE 1, and

FIGURE 3 is a similar View of a still further embodiment of the grab illustrated in FIGURE 1.

Referring first to the embodiment according to FIG- URE 1, the hydraulic grab comprises a pivoting turret 1 to which a jib 3 is articulated at 2. A beam 5 is pivotally mounted at 4 to the end of the jib 3, and supports a working tool or bucket 6 which is articulated at 7 to the beam 5.

An hydraulic jack 8, which may if required be of the double-acting type, is pivotally connected to the jib at 9 and to the beam at 10. A second hydraulic jack 11, which may if required be of the double-acting type, is pivotally connected to the turret 1 at 12 and to the beam 5 at 13. The jack 8 operates to extend or retract the beam 5 whilst the jack 11 effects oscillation of the beam to be controlled for the purpose of carrying out ground levelling work.

The jack 8 locks the beam relative to the jib 3, so that the jack 11 can effect inclination of the jib, in particular for unloading purposes.

A first rocking lever 15 is articulated at 14 to the end of the jib in the vicinity of the articulation 4 of the beam 5. A second rocking lever 16 is articulated at 17 to the beam at a point preferably situated in the vicinity of the articulation 7 of the bucket.

However, it must be understood that the articulation 17 and the articulation 7 may coincide, even though this arrangement does not appear to be very advantageous.

Preferably, there is a small distance between the articulation 4 and the articulation 14 in order to transmit to the tool the oscillations of the beam with respect to the jib, as will hereinafter be more fully described.

A first link 18 is pivoted at 19 to the beam 5, and at 20 to the rocking lever 15. A second link 21 is pivoted at 22 to the rocking lever 15, and at 23 to the rocking lever 16. Finally, a third link 24 is pivoted at 25 to the rocking lever 16, and at 26 to the bucket 6.

The link 21 consists of a double-acting hydraulic jack, enabling variation of the orientation of the bucket 6 relative to the ground, more particularly while materials in the said bucket are being unloaded.

The grab operates as follows: during ground levelling work, the jack 21 is locked and deformation of the articulated quadrilateral 4192014 due to oscillation imparted to the beam by the jack 11 is transmitted by the link 21, the rocking lever 16 and the link 24 to the bucket 6, which remains in a substantially constant position with respect to the ground. The beam therefore continually oscillates between the position illustrated in full line and the position illustrated in chain dot-ted line, the jib itself oscillating by a small amount about its articulation 2, since the bucket 6 is resting on the ground all the time.

If the length of the jack 21 is slightly altered during this operation, this varies the angle of attack of the bucket with respect to the material to be loaded, which can greatly facilitate penetration between blocks for example.

If it is now desired to unload the materials in the bucket 6, for example into a vehicle, the jack 8 is locked in the retracted position, as may be seen in that portion of the figure which is in chain dotted line, and the jack 11 is extended to the maximum. The jib 3 then lifts, imparting motion to the beam, with which it is now fast. When the bucket has attained the desired height the jack 21 is re tracted, causing the bucket to tip progressively, and the materials which it contains to be unloaded in controlled fashion.

Referring now to FIGURE 2 the jacks 8 and 11 of the embodiment illustrated in FIGURE 1 are replaced by the jacks 11a and 8a. The jack 11a is articulated directly to the jib 3, and serves only to control the inclination of the said jib, while the jack 8a enables oscillatory movement of the beam.5 to be controlled when the jack 11a is free to extend or retract.

Operation is in all respects similar to that hereinbefore described, and the jib 3 is caused to lift for unloading purposes when the jack 8a is locked in its extended position.

In the embodiment according to FIGURE 3 the beam is controlled in a manner similar to that illustrated in FIGURE 1. However, the link 21a articulated between the two rocking levers 15 and 16 is of fixed length whilst the link 18a is of variable length, and is in the form of an hydraulic jack as illustrated.

The characteristics of each of the embodiments of FIG- URES 2 and 3 may naturally be combined with one another without departing from the scope of the invention. In particular, it may be advantageous in some cases for both the links attached to each rocking lever to be articulated thereto at the same point. Likewise, the link 24 could be replaced by a jack, even though this arrangement does not appear to be very advantageous in view of the fact that this region of the apparatus is subject to damage by materials being loaded.

I claim:

1. A hydraulic grab adapted for ground levelling operations, comprising an oscillatable jib having a free end, a beam articulated to said end of the oscillatable jib, a tool pivotally supported from the beam and having an angular position relative to the ground, means coupled to said tool, beam and jib for controlling the angular position of the tool relative to the ground while the beam is oscillating on the jib, said means comprising a first rocking lever articulated to the beam and a second rocking lever articulated to the jib, and three links, the first of which is pivotally connected to the tool and to the first rocking lever, the second being pivotally connected to both rocking levers, while the third link is pivotally connected to the second rocking lever and to the beam, said first rocking lever having an axis of articulation where it is pivotally connected to the beam which is disposed in the vicinity of the pivotal connection between the tool and the beam, said second rocking lever having an axis of articulation where it is pivotally connected to the jib which is disposed in spaced relation with the location where the beam is pivotally connected to the jib but in the vicinity thereof.

2. A hydraulic grab according to claim 1, comprising means for adjusting the length of one of the links.

3. A hydraulic grab according to claim 2, wherein said means for adjusting the length of one of the links comprises a double-acting hydraulic jack.

4. A hydraulic grab according to claim 2, wherein the link pivoted to the beam and the second rocking lever comprises means permitting the latter link to be adjustable in length.

5. A hydraulic grab according to claim 2, wherein the link pivoted to the two rocking levers is adjustable in length.

References Cited by the Examiner UNITED STATES PATENTS 2,994,446 8/1961 Van Anwelaer et al. 214-138 3,080,076 3/1963 Randall 2141'38 3,080,077 3/1963 Schwellenbach 214-l38 3,120,315 2/1964 Johnson et :al 214-138 HUGO O. SCHULZ, Primary Examiner. 

1. A HYDRAULIC GRAB ADAPTED FOR GROUND LEVELLING OPERATIONS, COMPRISING AN OSCILLATABLE JIB HAVING A FREE END, A BEAM ARTICULATED TO SAID END OF THE OSCILLATABLE JIB, A TOOL PIVOTALLY SUPPORTED FROM THE BEAM AND HAVING AN ANGULAR POSITION RELATIVE TO THE GROUND, MEANS COUPLED TO SAID TOOL, BEAM AND JIB FOR CONTROLLING THE ANGULAR POSITION OF THE TOOL RELATIVE TO THE GROUND WHILE THE BEAM IS OSCILLATING ON THE JIB, SAID MEANS COMPRISING A FIRST ROCKING LEVER ARTICULATED TO THE BEAMS AND A SECOND ROCKING LEVER ARTICULATED TO THE JIB, AND THREE LINKS, THE FIRST OF WHICH IS PIVOTALLY CONNECTED TO THE TOOL AND TO THE FIRST ROCKING LEVER, THE SECOND BEING PIVOTALLY CONNECTED TO BOTH ROCKING LEVERS, WHILE THE THIRD LINK IS PIVOTALLY CONNECTED TO THE SECOND ROCKING LEVER AND TO THE BEAM, SAID FIRST LEVER HAVING AN AXIS OF ARTICULATION WHERE IT IS PIVOTALLY CONNECTED TO THE BEAM WHICH IS DISPOSED IN THE VICINITY OF THE PIVOTAL CONNECTION BETWEEN THE TOOL AND THE BEAM, SAID SECOND ROCKING LEVER HAVING AN AXIS OF ARTICULATION WHERE IT IS PIVOTALLY CONNECTED TO THE JIB WHICH IS DISPOSED IN SPACED RELATION WITH THE LOCATION WHERE THE BEAM IS PIVOTALLY CONNECTED TO THE JIB BUT IN THE VICINITY THEREOF. 